JPH08238911A - Penumatic tire suitable for traveling on icy and snowy road - Google Patents

Abstract

PURPOSE: To improve traveling performance on an icy road by axially dividing a block of a tread pattern into three sections of the center section and both sections, and providing a plurality of closed sipes for forming a plurality of microblocks on the center section, and connecting sipes for connecting the closed sipes. CONSTITUTION: A tread pattern of a snow tire is provided with many blocks 15 to 17 composed of two circumferential grooves 11 on the center part, circumferential grooves 12 on both sides, and transverse grooves 13. Respective blocks 15 to 17 are composed of three sections of the center sections a1 to a3 and both side sections b1 to b3 as seen from the axial direction, and a plurality of closed sipes 19 for forming a plurality of microblocks 18 are provided on the center section. Each single sipe 21 is provided on both sides of each closed sipe 19, and the closed sipes 19 are connected by a connecting sipes 20. The shape of the closed sipe 19 is formed into a round, elliptical, triangular, square, and hexagonal shapes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winter tire, and more particularly to a pneumatic tire having a tread pattern having excellent running performance on ice.

[0002]

2. Description of the Related Art Conventional so-called snow tires generally have a structure in which a zigzag main groove or a straight main groove continuous in the circumferential direction are combined with a lug groove, and a pattern in which a plurality of sipes are arranged substantially in parallel is provided. Yes, and the negative rate is 35-4 for both ice running performance and snow running performance.
5% was common. A typical example of a typical tread pattern applied to such a pneumatic tire for traveling on ice and snowy roads is shown in FIG.

As shown in FIG. 3, a conventional typical pneumatic tire for traveling on ice and snow roads has a center zigzag main groove 31 extending continuously in the tire circumferential direction at the center, and straight grooves 33 on both sides thereof, and further, a straight groove 33. Shoulder zigzag main grooves 32 are alternately arranged on the outer side in the tire width direction, and a large number of lug grooves 34 are arranged at intervals in the circumferential direction to connect these circumferential grooves, and these circumferential grooves 31, 32, 33 are arranged. A plurality of block rows 36 are formed by the lug grooves 34 and the plurality of sipes 35 are arranged substantially in parallel in each block, and a tread pattern with a negative ratio of 35 is provided. Demonstrate a performance against.

However, in recent years, the need for a tire that can exhibit more excellent on-ice performance, that is, turning performance and braking performance than a conventional tire on a frozen road surface having a reduced friction coefficient has been particularly increasing in recent years.

In order to improve the on-ice performance, the frictional force is increased by increasing the ground contact surface area (positive), and the digging effect is obtained by increasing the number of sipe (density) and the edge component. It is possible to take measures such as enhancing the edge effect). Furthermore, it has been found that it is important to remove the water film that springs to the ground contact surface, especially on ice near 0 ° C. For this purpose, it is effective to increase the sipe density.However, if the sipe density is increased too much, the rigidity of the block will decrease too much, causing uneven wear, and at the same time, the bending deformation of the block will decrease the ground contact area, rather reducing the performance on ice. There is a problem to do.

Foamed rubber as disclosed in Japanese Unexamined Patent Publication No. 62-283001 is often used for a tread of a tire running on an icy and snowy road. However, since it is softer than a general tread rubber, a foamed rubber is used. When using sipe with high density in the adopted tread, it is important to secure block rigidity.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a new tread pattern which is excellent in running performance on snow, especially on ice. The object of the present invention is
A pneumatic tire having a snowy road running pattern suitable for a tread made of a relatively soft rubber such as the foamed rubber.

[0008]

DISCLOSURE OF THE INVENTION The present invention is a tread pattern having a large number of blocks provided with a plurality of sipes, the blocks each having three regions, that is, a central region and regions on both sides thereof, as viewed in the axial direction. Two types of sipes, a plurality of closed sipes forming a plurality of microblocks and a connecting sipes for connecting the closed sipes, are arranged in the central area, and a plurality of single sipes are arranged in the both side areas. It is a pneumatic tire having a tread pattern.

[0009]

[Function] The sipe of the studless pattern has a water removing effect of cutting the water film spread in the tread in addition to the edge effect of the sipe edge. When one independent block touches the ice surface, the water film in the block is drained out of the block surface by the open sipe opening in the adjacent main groove, but the central area of the block away from the main groove is drained. Tends to be difficult. Therefore, it is advantageous for drainage to make the sipes in the center of the block dense. However, if the sipes on the entire surface of the block are made dense, the edge component and the drainage effect are improved, but if they are left as they are, the rigidity of the block is lowered and the effective ground contact area is reduced due to the deformation of the block, resulting in deterioration of the braking performance and the like.

Therefore, by closely arranging the closed sipes only in the central portion of the block as in the structure of the present invention,
Both the drainage of the water film on ice and the block rigidity are achieved.
Further, since the closed sipes in the central portion of the block have a circumferential component, it becomes easy to secure rigidity in the front-rear direction. Further, by connecting the closed sipes in the central portion of the block, the sipes communicate with each other to allow water to pass therethrough, so that the water removing effect is enhanced. However, since the sipe is a closed type, the block rigidity at the center of the block is lowered, so the close sipes are spaced apart and the closed sipes are connected in the radial direction by connecting sipes to ensure the block rigidity and the water removal effect. Is improving. Since the connecting sipes extend substantially in the axial direction, they exhibit a high edge effect.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 show a pattern A according to the first embodiment and a pattern B according to the second embodiment. In both cases, the tire size is 185 / 70R14, the tread width TW is about 148 mm, and the negative ratio is 28%. The width of the sipes applied is 0.5 mm.

As shown in FIG. 1, the tread pattern of the first embodiment has a large number of blocks formed by two central circumferential grooves 11, circumferential grooves 12 on both sides, and transverse grooves 13. It is equipped with 15, 16 and 17. Here, the central circumferential groove 11 and the lateral circumferential groove 12 have groove widths of 5 mm and 6 mm, respectively, and the transverse groove 13 has a groove width of 6 mm. The transverse groove 13 has a narrow transverse groove portion 14 having a narrow groove width such that both side walls of the groove 1 come into close contact with each other at the time of contact with the ground, and the narrow transverse groove portion 14 has the front and rear blocks 1 at the time of contact with the ground.
Continuity is imparted to 5, 15, 16, 16, 17, and 17, and the groove width thereof is 2 mm.

The blocks 15, 16 and 17 respectively have central sections a1, a2 and a3 and their side sections b as viewed in the axial direction.
Each block has a plurality of closed sipes 19 forming a plurality of microblocks 18 in a central region. In addition, each block has a closed sipe 19 forming a single microblock or a plurality of microblocks in its central region, and a single sipe 21 is provided on each side of the single closed sipe to provide a plurality of closed sipes. The closed sipes are connected by the connecting sipes 20, and the single sipes 21 are provided on both sides of the closed sipes as in the case of the above-mentioned singular.

In the pattern A, the sipe center area a1 of the block 15 is 12 mm, and the both side area b1 is 4.5 m.
m, the sipe center area width a2 of the block 16 is 12 mm, the both side area width b2 is 9 mm, the sipe center area width a3 of the block 17
Is 12 mm and the width b3 on both sides is 4.5 mm.

The shape of the closed sipe 19 provided in the central region of each block 15, 16 and 17 may be any shape such as a circle, an ellipse, a triangle, a quadrangle, a hexagon, etc. In A, the shape of the closed sipe 19 is an irregular hexagonal shape as illustrated.

In the case of pattern A, both the connecting sipe and the single sipe have a linear shape. The connecting sipe and the single sipe connected to each of the closed sipes extend substantially in the axial direction of the tread. In addition, in the embodiment, each connecting sipe and the single sipe are provided with a slight inclination with respect to the radial direction.

In the pattern B of the embodiment shown in FIG. 2, the configuration of each block is almost the same as that of the pattern A, but the single sipe 21 connecting the closed sipe 19 and the end of each block has a zigzag wave shape. This is a bent sipe. The connecting sipe that connects the plurality of closed sipes 19 is a linear sipe. Also in this embodiment, each sipe of each block has the pattern A
Similarly to the above, it is provided slightly inclined with respect to the axial direction.

In a pneumatic tire for running on ice and snowy roads, a foam rubber having a low hardness is often used for a tread in order to increase a friction coefficient, and a large number of sipes are arranged in the block. As a result, a phenomenon may occur in which the tire tread rigidity is insufficient and the tread rubber (block) buckles directly under a load. In order to prevent this, it is necessary to secure the rigidity in the tread center region where the ground contact pressure is high. In the present embodiment, the continuity provided by the narrow transverse groove portion 14 ensures circumferential tread rigidity.

[0019]

[Effect] The tires having the pattern A which is the first embodiment of the present invention, the pattern B which is the second embodiment, and the conventional pattern are measured and compared under the same test conditions for cornering on ice, braking on ice and traction on ice, respectively. Then, as shown in Table 1 below, it can be understood that various characteristics of both patterns of the present invention are improved as compared with the conventional pattern.

[Table 1] Test conditions: Inner pressure 2.0km / cm, load equivalent to two passengers riding on ice Cornering on ice: Time measurement when circled on 20R ice disc Brake on ice: Braking distance when full braking from 20km / h on ice disc Measurement of ice traction: 100m from 20km / h on the ice plate
Measurement of braking time when fully accelerated

[0020]

[Brief description of drawings]

FIG. 1 is a plan view of a first embodiment of the present invention.

FIG. 2 is a plan view of a second embodiment of the present invention.

FIG. 3 is a plan view of a conventional example.

[Explanation of symbols]

 11 Central Circumferential Groove 12 Circumferential Grooves on Both Sides 13 Transverse Groove 14 Narrow Transverse Groove 18 Microblock 19 Closed Sipe 20 Continuous Sipe 21 Single Sipe

Claims (1)

[Claims] 1. A tread pattern having a plurality of blocks to which a plurality of sipes are applied, wherein the blocks are composed of a central region and three regions on both sides thereof in the axial direction, and a plurality of microblocks are provided in the central region. Two types of sipe, a plurality of closed sipes forming a line and a connecting sipe that connects the closed sipes, are arranged, and a plurality of single sipes are arranged in the both side areas. Suitable for pneumatic tires.